Many surgical procedures involve driving an implant into bone. Various implants can be driven into bone at any of number of locations within a patient's body for a variety of purposes. For example, when repairing tears in the cruciate ligaments of the knee, one common procedure involves driving one or more cross-pins into a patient's femur to secure a ligament graft within a bone tunnel formed in the femur. DePuy Mitek, by way of further example, provides its RIGIDFIX absorbable pins for use in this type of procedure. As shown in FIGS. 1A and 1B, the RIGIDFIX absorbable pins 102 can be used to secure either a soft tissue graft 104 (shown in FIG. 1A) or a so-called bone-tendon-bone graft 106 (shown in FIG. 1B) within a bone tunnel formed in a patient's femur 108.
As shown in FIG. 2, the pins can be driven into the patient's femur 108 through a delivery cannula 202 that is inserted partway into the femur at the correct alignment. After the delivery cannula 202 is inserted, a pin 102 can be placed into the delivery cannula 202 at its proximal end and driven into the bone using a driver shaft 302 and an impacting tool, as shown in FIG. 3. A number of different impacting tools can be used, including, for example, a hammer.
In many procedures, an implant being driven into bone in this manner must be delivered to a particular depth or undesirable complications may result. In the case of cruciate ligament repair using cross-pins, for example, it can be desirable to drive the pins 102 to a depth that leaves an amount of clearance between a distal end of the pins 102 and the outer surface of the lateral cortex of the femur 108, as shown in FIG. 4. Overdriving the pins 102 can result in too little clearance between the distal end of the pins 102 and the outer surface of the lateral cortex, or even protrusion of the pin through the outer surface of the femur, as shown in FIG. 5.
Accordingly, there is a need for novel devices, systems, and methods for controlling the depth of insertion of a medical implant. In particular, there is a need for improved devices, systems, and methods for both indicating to a user that a predetermined insertion depth has been reached and preventing further insertion of the implant even if the indication is ignored.